How pendulum clocks oscillate in sync decoded

Scientists have come up with the most accurate and detailed description behind how two pendulum clocks, hung from the same wooden structure, always oscillate in synchronicity, 350 years after the effect was discovered.
The effect, called 'Huygens synchronisation', was discovered in 1665 by prominent Dutch mathematician Christiaan Huygens.
Two pendulum clocks Huygens built himself and hung on the same structure appeared time and again to swing nicely to and fro with the same frequency regardless of their starting position.
Lacking the requisite mathematics at the time, Huygens contended that the effect was being caused by tiny vibrations in the wooden structure on which the clocks were hanging.

Around 350 years later, researchers from Eindhoven University of Technology in Netherlands and their colleagues found that Huygens' explanation was right.
They performed a modern variant of Huygens' experiment whereby two pendulum clocks specially made for the purpose.

In addition to taking extensive measurements, they analysed and simulated the effect using the most detailed mathematical model developed for this experiment.
This enabled them to dissect the mechanism behind the synchronisation in detail, and disproved the theory proposed two years ago that the synchronisation was attributable to acoustic pulses.
They also discovered what variables determine whether the clocks swing in parallel with or counter to each other, something that Huygens did not observe.

Another new discovery is that pendulum clocks are not only synchronous but also move more slowly over time and thus are not very reliable timekeepers, researchers said.
That such an effect has kept scientists fascinated for a good 350 years is partly due to the fact that many similar occurrences of synchronisation are present in engineering and in nature, like imbalanced rotor motion or the human heartbeat, they said.
The findings help researchers understand synchronisation in all kinds of oscillating systems, such as the biological rhythms of the human body.
There are also indications that certain epileptic attacks are caused by the synchronisation of neurons that takes place in the brain, researchers said.

The findings were published in the journal Scientific Reports.